1. Field of the Invention
This invention relates to a valve core which is mounted in a core mounting hole formed in a counterpart member to open and close the core mounting hole.
2. Description of the Related Art
A conventional valve core comprises a cylindrical core body fixed in a core mounting hole formed in a counterpart member on which the valve core is to be mounted. A moving shaft extends through the core body so as to be directly driven. The moving shaft has one end on which a pair of flanges are provided. A sealing member is held between the flanges. The sealing member is caused to adhere closely to an inner circumferential edge of an opening of the core body so as to close the core mounting hole. In the above-described conventional valve core, however, the sealing member held between the flanges sometimes drops off.
Therefore, an object of the present invention is to provide a valve core which can prevent the sealing member from dropping off from between the flanges.
The present invention provides a valve core comprising a generally cylindrical core body fixed in a core mounting hole formed in a counterpart member, the core body having an open end, a moving shaft extending through the core body so as to be directly driven, the shaft having an end, a pair of flanges provided on the end of the shaft, a generally annular sealing member held between the flanges so as to adhere closely to an inner circumferential edge of the open end of the core body or an inner circumferential face of the core mounting hole to thereby close the core mounting hole, and a pair of engagement portions formed in either flange and the sealing member so as to be brought into a concavo-convex engagement with each other to limit deformation of the sealing member causing an increase in a diameter thereof.
In the above-described valve core, the sealing member is held between the paired flanges, and the engagement portions are brought into concavo-convex engagement with each other between the flange and the sealing member, whereby deformation of the sealing member causing spread of the diameter thereof is limited. Accordingly, even where adhering closely to the inner circumferential edge of the open end of the core body or the Inner circumferential face of the core mounting hole, the sealing member is moved during fixation at the flange side when the valve core is opened. Consequently, the sealing member can be prevented from dropping off from between the flanges although it sometimes drops off in the conventional valve cores.
More specifically, either one of the engagement portions is preferably a protrusion protruding from the flange and biting into the sealing member. In this construction, the protrusion pushes the sealing member such that a part of the sealing member is depressed. The protrusion and the depression are brought into concavo-convex engagement.
Further, the engagement portions preferably include a protrusion formed by protruding a part of the sealing member toward one of the flanges and a depression formed by depressing a part of said one flange so as to correspond to the protrusion. Further, one of the flanges located farther away from the core body than the other preferably includes a butting portion protruding from said flange toward the sealing member, and a portion of said flange located outside the butting portion is opposed to the sealing member with a space defined therebetween. Consequently, a deformed part of the sealing member is located in the space thereby to be protected.
Additionally, the inner circumferential edge of the open end of the core body is preferably formed with an inner inclined face gradually spread toward a distal end thereof, the sealing member being caused to adhere closely to the inner inclined face, and the flange has an outer circumferential face on which an outer inclined face is formed so as to abut against the inner inclined face. In this construction, the outer inclined face formed on the outer circumferential face of one of the flanges is caused to abut against the inner inclined face of the core body, whereby the flange is aligned and axially positioned. The sealing performance of the valve core and be improved since the sealing member adheres closely to the inner inclined face in the aligned and positioned state of the flange.